In this review, we will be comparing Imagine XB and Q150, two Passive Bookshelf speakers from PSB and KEF.
Let's have a brief look at the main features
of PSB Imagine XB and KEF Q150 first before getting into our more
detailed comparison.
| Key Specs | PSB Imagine XB | KEF Q150 |
|---|
| Design | 2-way | 2-way |
|---|
| Uni-Q driver | — | 11th Generation Uni-Q |
|---|
| Tweeter | 1" Hard-Dome | 1" Dome |
|---|
| Woofer | 5.25" Clay/Ceramic/Poly | 5.25" Aluminum |
|---|
| Frequency response | 55-23k Hz | 51-28k Hz |
|---|
| Sensitivity | 87 dB | 86 dB |
|---|
| Impedance | 8 ohms | 8 ohms |
|---|
| Power range | 20-150 watts | 10-100 watts |
|---|
| Weight | 5.60kg / 12.3lbs | 5.60kg / 12.3lbs |
|---|
| Dimensions (H x W x D) | 12" x 6.75" x 10.75"
302 x 170 x 271mm | 11.9" x 7.0" x 10.9"
303.0 x 180.0 x 278.0mm |
|---|
What size room are the PSB Imagine XB and KEF Q150 speakers good for?
The size of the room in which you are planning to use these loudspeakers is an important decision
factor. Here we have compared their suitability to various sizes of environments considering their size
and max power parameters:
| Listening Environment* |
PSB Imagine XB |
KEF Q150 |
| Near-field |
Poor |
Average |
| Small Room |
Average |
Good |
| Mid-size Room |
Good |
Average |
| Large Room |
Average |
Poor |
| Very Large Room |
Poor |
Bad |
(* Approximate Room sizes: Small < 100sq. ft / 9 m2,
Mid-size: 100-220 sq. ft / 9-20 m2, Large 220-400 sq. ft / 20-36 m2, Very Large: >
400 sq. ft / 36 m2.
Average Floor Height: 9" / 2.7m. Typical room sizes differ from country to country, and the actual
listening experience changes depending on floor height, room shape, surface materials, listening
position, speaker locations, etc.)
The sections below take each area in turn: drivers, frequency response, physical size and what you get in the box.
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Drivers
Both Imagine XB and Q150 are 2-way speakers.
PSB Imagine XBKEF Q150
TweeterWoofer
Front view, drawn to scale - cabinets and drivers share one scale, so sizes are directly comparable. Hover a driver for its size.
| Driver |
PSB Imagine XB |
KEF Q150 |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 5.25-inch
|
1 x 5.25-inch
|
Imagine XB features a 1" Titanium Dome with Ferrofluid Hard-Dome Tweeter and 1 x 5.25" Clay/Ceramic/Poly Woofer with a Crossover frequency at 1800Hz. On the other hand, the Q150 features a 1" vented aluminum Dome Tweeter and 1 x 5.25" Aluminum Woofer with a Crossover frequency at 2500Hz.
Frequency Response
Imagine XB has a frequency range of 55-23k Hz whereas Q150 has a frequency range of 51-28k Hz. With a minimum frequency of 51Hz, the Q150 can go slightly deeper then the Imagine XB's min frequency of 55Hz.
The graph below depicts how these two speakers compare with the max, min and average Low Frequency values of other speakers in the Bookshelf class in our database.
Low Frequency
Bookshelf Speakers
Neither pair reaches down to 20Hz, the usual definition of full-range, which is normal for speakers of this size. If you want the bottom octave for movies or bass-heavy music, add a subwoofer to whichever you choose. Visit our Powered Subwoofers section to find out more about the available options.
Impedance and Sensitivity
Imagine XB and Q150 have the same Impedance of 8 ohms but where they differ is the sensitivity levels. Imagine XB sensitivity is rated at 87 dB and the Q150's is at 86 dB. This 1 dB difference makes the PSB Imagine XB a more sensitive speaker compared to KEF Q150, hence will play louder with the same amount of watts.
Sensitivity
Bookshelf Speakers
Power Range
Power
range is the range of input power in watts RMS that a loudspeaker is designed to handle. Staying
within that range gives nominal performance; driving the speaker beyond its maximum wattage can damage it.
Imagine XB can handle a max power of 150 watts RMS, whereas Q150 has a max power handling value of 100 watts RMS, 50 watts less than the Imagine XB.
Note that higher power handling does not make a speaker louder: that depends mainly on
sensitivity and impedance. The calculator below shows how loud each of these actually plays
on a real amplifier.
Which plays louder on your amplifier?
Starting with a popular amplifier — change it to the one you own, or any you are
considering, and watch both numbers move.
Input Type and Bi-Amping / Bi-Wiring
Imagine XB features Post type posts and Q150 has a Post type posts. None of these speakers feature bi-amping/bi-wiring.
KEF Q150's Post terminals
Cabinet Type and Port Position
Both Imagine XB and Q150 have rear firing ports. Rear ported speakers generally need more room between the backside of the speaker and the wall compared to sealed and front/bottom ported speakers. Placing the speakers too close to the walls may cause the bass to sound boomy.
If you are limited in space and can't get the speakers away from the backwall, check our Speakers with Front Firing Ports page.
KEF Q150 Port
Physical Specs
The size of a speaker can sometimes be an important decision factor due to space constraints or in some cases purely for esthetic reasons. In this section, we are going to compare PSB Imagine XB's and KEF Q150's external dimensions. PSB Imagine XB has external dimensions of 302 x 170 x 271mm (12inch x 6.75inch x 10.75inch) whereas KEF Q150 has external dimensions of 303.0 x 180.0 x 278.0mm (11.9 x 7.0 x 10.9inch).
KEF Q150 is clearly the larger of the two speakers. Its body is 10mm wider, 1mm taller and 7mm deeper than PSB Imagine XB.
Base Surface Area Comparison
Base surface area of a loudspeaker may become a determining factor when the space in your room or desk is limited.
The base surface area of the PSB Imagine XB is approximately 460.0cm2 / 71.3inch2 and base area of the KEF Q150 is approximately 500.4cm2 / 77.6inch2. The Imagine XB requires 8% less surface area than the Q150 which gives it a small advantage on placement in tight spaces.
Weight Comparison The weight of a loudspeaker can become an important factor if you need to move and reposition the unit often. Weight of a speaker can also "sometimes" be an indicator of the rigidity of the enclosure and the quality of the internal components used. The PSB Imagine XB weighs 5.60kg / 12.3lbs and the KEF Q150 weighs 5.60kg / 12.3lbs.
Here is a comparison of how Imagine XB and Q150's weights compare with the average, max and min weights in Passive Bookshelf class.
Weight
All Bookshelf Speakers
What's in the Box of PSB Imagine XB?
Here are the items that are included inside the box of Imagine XB:
- 2 Bookshelf loudspeakers
- 2 Grilles
- 8 Rubber feet
- Quick Start Guide
- Warranty Card
What's in the Box of KEF Q150?
Here are the items that come with the Q150:
- 2 Bookshelf loudspeakers
- 2 Foam port plugs
- 8 Self-adhesive rubber feet
- Owner's Manual
- Warranty Registration Card
 Max Input Power |
150 watts
vs
100 watts
|
Handle more power from your amplifier |
 Sensitivity |
87 dB
vs
86 dB
|
Play louder with same amount of amplification power |
 Minimum Impedance |
4 ohms
vs
3.7 ohms
|
Very low impedance levels puts more pressure on amplifier |
 Height |
302mm
vs
303mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
460cm2
vs
500cm2
|
Takes less floor space |
 Low Frequency Response |
51 Hz
vs
55 Hz
|
Generates deeper bass |
 High Frequency Response |
28k Hz
vs
23k Hz
|
Generates higher frequency |
 Price per pair* |
600USD
vs
649USD
|
costs less (*prices may change depending on the seller, location and time) |
| General |
PSB Imagine XB |
KEF Q150 |
| Brand |
PSB |
KEF |
| Speaker Type |
Bookshelf speakers |
Bookshelf speakers |
| Power Range |
20-150 watts |
10-100 watts |
| Sensitivity |
87 dB |
86 dB |
| Impedance |
8 ohms |
8 ohms |
| Impedance |
4 ohms |
3.7 ohms |
| Frequency Response |
55-23k Hz |
51-28k Hz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
5.25" |
5.25" |
| Woofer Composition |
Clay/Ceramic/Poly |
Aluminum |
| Woofer Surround Material |
Rubber |
Rubber |
| Tweeter Size |
1" |
1" |
| Tweeter Type |
Hard-Dome |
Dome |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
1800Hz |
2500Hz |
| Firing Direction |
rear |
rear |
Physical Specs |
|
|
| Height |
302.0mm (11.9") |
303.0mm (11.9") |
| Width |
170.0mm (6.7") |
180.0mm (7.1") |
| Depth |
271.0mm (10.7") |
278.0mm (10.9") |
| Weight |
5.60kg (12.3lbs) |
5.60kg (12.3lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Finish |
MDF/Wood-grain |
MDF/Vinyl-wrapped |
| Available Colors |
Black |
Black, Walnut, White |
| Mounting Bracket |
|
No |
| Recommended Stand Height |
24-26" |
18-24" |
| Grille |
Yes |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Biamp Inputs |
No |
No |
Other |
|
|
| Parts Warranty |
5 Years |
5 Years |
| Labor Warranty |
5 Years |
5 Years |
A generation apart: KEF Q150 is the newer design, against a 2013 model. Newer is not automatically better, but the older one is more likely to be discounted or near run-out.
| Area | Better | Why |
|---|
| Bass |
B |
KEF Q150 digs deeper - 51Hz against 55Hz. A subwoofer would even that out. |
| Amplifier needs |
evenly matched |
Similar sensitivity (87dB vs 86dB) - both want much the same power. |
| Headroom |
A |
PSB Imagine XB takes more power (150W vs 100W) - more in hand in a big room. |
| Size |
depends |
Similar cabinet size - neither is easier to fit. |
| Expandability |
depends |
Neither adds bi-amping, a sub output or height drivers. KEF Q150 sits in a wider range (7 models), so a matched surround system is easier later. |
| Price |
evenly matched |
Much the same money ($649 vs $600 a pair). |
A PSB Imagine XB
B KEF Q150
depends neither is better in the abstract - it turns on your room, placement or how you will use them.
Only specs published for both speakers are judged; anything missing on either side is left out rather than guessed.
Which should you choose?
Neither runs away with it - they trade advantages. Let the "depends" rows and your own room settle it. Match it to your room: we rate PSB Imagine XB the better fit for a mid-size room and a large room, and KEF Q150 for near-field listening and a small room.
And remember what a spec sheet cannot show: how each looks in your room and whether the finish suits it, what dealer support and warranty are like where you live, and how they actually sound to you. If you can hear them first - ideally with your own music - that will tell you more than any number above.